In a statement, Mr Low's parents Martyn and Helen Low said they felt "totally let down by the authorities".

"We fail to understand why Turkey would allow a Bulgarian citizen [Sali Ahmet] suspected of murder to be set free in their own country instead of handing him over to the Bulgarian authorities to start the deportation process back to southern Cyprus to stand trial for the despicable and senseless act of violence against our son George and Ben, a lifelong friend.

"Now 11 months on both men are free to enjoy their lives. We will not let this rest."

Image caption
Ben Barker was repeatedly stabbed at the same time as his friend

'Too late'

Ben Barker, 22, who survived the attack, said he was "upset, disgusted and angry" that the men had been released.

"We've had quite a lot of lack of information, and it's always been in the back of my mind that it might go this way.

"It's looking like we're not going to get any justice for George."

Gareth Johnson the Conservative MP for Dartford, said he was also in regular contact with the Foreign Office "but frankly it's perhaps now too late".

He added he had met the ambassador from northern Cyprus, who had claimed the authorities were not receiving "the evidence from southern Cyprus that enables them to take action".